• Corpus ID: 189811976

Modal Pushover-Based Scaling of Two Components of Ground Motion Records for Nonlinear RHA of Buildings

@inproceedings{Reyes2010ModalPS,
  title={Modal Pushover-Based Scaling of Two Components of Ground Motion Records for Nonlinear RHA of Buildings},
  author={Juan Carlos Reyes},
  year={2010}
}

• J. Reyes
• Published 2010
• Engineering

The accuracy and efficiency of the modal-pushover-basedscaling (MPS) procedure is evaluated here by applying it to an existing 9-story building, symmetric in plan. The computer model developed for the building is validated against motions of the building recorded during the 2008 Chino-Hills earthquake. It is demonstrated that nonlinear response history analysis (RHA) of the building for a small set of records scaled by the MPS procedure provided a highly accurate estimate of the engineering demand parameters, accompanied by significantly reduced record-to-record variability of the responses. Furthermore, the MPS procedure is shown to be much superior to the procedure specified in the ASCE/SEI 705 standard for scaling two components of ground motion records. Introduction The earthquake engineering profession has been moving away from traditional code procedures to performance-based procedures for evaluating existing buildings and proposed designs of new buildings. Although nonlinear static (or pushover) analysis continues to be used for estimating seismic demands, nonlinear response history analysis (RHA) is now being increasingly employed. In the latter approach, engineering demand parameters (EDPs)—floor displacements, story drifts, member forces, member deformations, etc.—are determined by nonlinear RHA of a computer model of the building for an ensemble of multi-component ground motions. Fraught with several challenging issues, selection and scaling of ground motions necessary for nonlinear RHA remains the subject of much research in recent years. The objective of amplitude scaling procedures is to determine scale factors for a small number of records such that the scaled records provide an accurate estimate of median structural responses, and, at the same time, are efficient, i.e. reduce the record-to-record variability of response. Development of such procedures has come a long way from scaling records to match target peak ground acceleration, target elastic response spectrum at the fundamental vibration period T1 of the structure, some combination of the spectral ordinates at the first two vibration periods, or the inelastic response spectrum at T1. A convenient summary of amplitude scaling methods was compiled in PEER (2009); individual references are too numerous to list here. Recently, developed is a modal-pushover-based-scaling (MPS) procedure for selecting and scaling earthquake ground motion records in a form convenient for evaluating existing structures and proposed designs of new structures (Kalkan and Chopra, 2010). This procedure explicitly considers structural strength, determined from the first-“mode” pushover curve, and determines a scaling factor for each record to match a target value of the deformation of the first-“mode” inelastic SDF system. The MPS procedure has proven to be accurate and efficient for low-, medium-, and high-rise buildings with symmetric plan subjected to one component of ground motion (Kalkan and Chopra, 2010). The MPS procedure has been extended to scale two horizontal components of ground motion for use in three-dimensional analysis of structural systems (Reyes, 2009). This paper investigates the accuracy and efficiency of the MPS procedure for a 9-story symmetric-plan building and compares it against the scaling procedure recommended in the ASCE/SEI 7-05 standard (ASCE, 2006). GROUND MOTION RECORDS The twenty-eight records selected for this investigation [listed in Reyes (2009)] were recorded from earthquakes with moment magnitude, 6.5 w M  at distances ranging from 7 to 28 km. Because the twenty-eight ground motions selected were not intense enough to drive the building considered far into the inelastic range—an obvious requirement to test any scaling procedure—they were amplified by a factor of 3.0; the resulting 28 ground motions are treated as “unscaled” records